package 所有的题类.F.树;

import 所有的题类.ZA.链表.TreeNode;

import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.Queue;

public class 二叉树的层序遍历 {

    public static void main(String[] args) {
        int[]array={1,2,3,4,5,6,7,8,9,10,11,12,13};
        TreeNode treeNode = arrayToTreeNode(array, 0, array.length - 1);
        cengXuBianLi(treeNode);
    }

    /**
     * 层序遍历二叉树
     * @param root
     * @return
     */
    public static void cengXuBianLi(TreeNode root){
        List<List<Integer>> listList=new ArrayList<>();
        Queue<TreeNode> queue = new LinkedList();
        queue.add(root);
        while(!queue.isEmpty()){
            //备份一份Queue;
            List<Integer> level=new ArrayList<>();
            int size=queue.size();
            for (int i = 0; i < size; i++) {
                TreeNode poll = queue.poll();
                level.add(poll.val);
                if(poll.right!=null){
                    queue.add(poll.right);
                }
                if (poll.left != null) {
                    queue.add(poll.left);
                }
            }
            listList.add(level);
        }
    }

    public static TreeNode arrayToTreeNode(int[]array,int left,int right){
        TreeNode root=null;
        if(right>=left){
            int mid=(left+right+1)/2;
            root = new TreeNode(array[mid]);
            TreeNode leftNode = arrayToTreeNode(array, left, mid-1);
            TreeNode rightNode = arrayToTreeNode(array, mid + 1, right);
            root.left=leftNode;
            root.right=rightNode;
        }else{
            root=null;
        }
        return root;
    }

}
